Western Sichuan is located in the transitional zone between the Qinghai-Tibet Plateau and the Sichuan Basin, with frequent geological activities and the superposition of complex factors such as rivers, glaciers and rainfall in the region, resulting in the existence of many ancient landslide groups. Open-pit mining is a long-lasting human activity, which will not only change the geomorphological characteristics in the original area, but also induce the revival of ancient landslides. Heavy rainfall is one of the important causes of geological disasters. Taking it as the main cause, combined with relevant monitoring data, the types of deformation inducing factors of ancient landslides in large open pit mines in western Sichuan was analyzed, the response relationship between the deformation of ancient landslides and rainfall was obtained, a finite element calculation model was established, the seepage characteristics, deformation characteristics and stability change law of ancient landslides under heavy rainfall were calculated and analyzed, and the resurrection mechanism of such ancient landslides was revealed. The research results are of reference value for deepening the understanding of the ancient landslide of large open pit in western Sichuan, and are of great significance for completing the landslide control and disaster prevention under the action of rainfall.